I tired ubuntu 14.04 and debian 7.6....both has the same issue...

1. Create VM with one NIC "eth0"...then run once and insert the cloud-init data and make it up...

2. Powerdown the VM.

3. Add extra ip "eth1"...

4. run once and insert the cloud-init data and make it up...

5. VM successfully come up but removed the eth0 and loopback address config from /etc/network/interfaces file....

6. Now from ifconfig it displays only eth1...becasue eth0 and loopback config removed by eth1..

Thanks,

Punit